Struts and Connection pooling my servlet DB connections ...

I have done extensive work using the MVC approach to application development and i am ready to move on to the nextlevel. THis next level, for me, is the STRUTS frame work of web application design. For the model portion of STRUTS, is there connection pooling contained with in the class structure or do we have to add this connection pooling ourselves. I have already develpoed DB / servlet connection pooling classes and i am looking to incorporate them into the STRUTS frame work, do i need to or is there some thing there already?

Well, to be J2EE you could use an implementation of javax.sql.DataSource which also implements connection pooling.
I use the one that's packaged in tomcat : exolab's tyrex. http://tyrex.exolab.org

Similar Messages

How to implement a connection pooling in servlet

hi all,
how to implement a connection pooling in servlet.i want to know how to implement it in tomcat in a struts based environment.
any input to the topic is appreciated.
Thanks
Sudha

Take a look at JNDI
http://jakarta.apache.org/tomcat/tomcat-4.1-doc/jndi-datasource-examples-howto.html

Oc4j connection pool: too much INACTIVE connections

I am publishing an application - developed using Eclipse and previously published in Tomcat (where it works perfectly for a long time) - within corporate servers using Oc4j version 10.1.3. The database server is Oracle 9g.
After the deployment operation, the application seems to work, but that happens during the work by users, there are still many connections whith status "INACTIVE", until to complete all the available connections.
The datasource is set as follows:
<connection-pool name="ConnectionPoolRichiestaPubblicazione">
<connection-factory factory-class="oracle.jdbc.pool.OracleDataSource"
user="REDAZIONE"
password="password"
url="jdbc:oracle:thin:@(DESCRIPTION=(FAILOVER=ON)
     (ADDRESS_LIST=(LOAD_BALANCE=ON)
     (ADDRESS=(PROTOCOL=TCP)
     (HOST=10.146.2.86)(PORT=1521))
     (ADDRESS=(PROTOCOL=TCP)(HOST=10.146.2.86)(PORT=1521)))
     (CONNECT_DATA=
(SERVER=DEDICATED)
(SERVICE_NAME=XE)
(FAILOVER_MODE=(TYPE=SELECT)(METHOD=BASIC)(RETRIES=180)(DELAY=5))))">
</connection-factory>
</connection-pool>
<managed-data-source
jndi-name="jdbc/RichiestaPubblicazioneDS"
name="RichiestaPubblicazioneDS"
connection-pool-name="ConnectionPoolRichiestaPubblicazione" />
The java code to establish a connection is as follows:
private Connection creaConnessioneDataSource(String nomedatasource) throws ConnessioneException{
          LOGGER.debug("START");
          try {
               InitialContext context = new InitialContext();
               DataSource ds = (DataSource)context.lookup(nomedatasource);
               LOGGER.debug("URL DATASOURCE : " + ds.getConnection().getMetaData().getURL());
               LOGGER.debug("USERNAME : " + ds.getConnection().getMetaData().getUserName());
               this.conn = ds.getConnection();
          catch( Exception e ) {
               LOGGER.error("Errore nella connessione tramite datasource : " + StringUtils.getCustomStackTrace(e));
          LOGGER.debug("END");
          return this.conn;
Connections and statements are closed using the following methods:
     public boolean chiudi(Connection conn){
          LOGGER.debug("START");
          boolean esito = false;
          if (conn != null){
               try {
                    conn.close();
                    esito = true;
                    LOGGER.debug("Connessione chiusa");
               catch (SQLException e) {
                    LOGGER.error("Eccezione nella chiusura della connessione : " + e);
          LOGGER.debug("END");
          return esito;
     public boolean chiudi(Statement stmt){
          LOGGER.debug("START");
          boolean esito = false;
          if (stmt != null){
               try {
                    stmt.close();
                    esito = true;
                    LOGGER.debug("Statement chiuso");
               } catch (SQLException e) {
                    LOGGER.error("Eccezione nella chiusura dello statement : " + e);
                    e.printStackTrace();
          LOGGER.debug("END");
          return esito;
Here are a couple of examples of code that interact with the database:
     public List<StatoRichiestaSintesi> getElencoStatiRichieste() throws ConnessioneException{
          LOGGER.debug("START");
          List<StatoRichiestaSintesi> listaStati=new LinkedList<StatoRichiestaSintesi>();
          LOGGER.debug("Apriamo connessione e statement");
          Connection conn = databaseManager.creaConnessioneDataSource(datasource);
          Statement stmt = databaseManager.creaStatement(conn, false);
          String sql="SELECT * FROM STATORICHIESTA";
          try {
               ResultSet rs = stmt.executeQuery(sql);
               while(rs.next()){
                    StatoRichiestaSintesi temp=new StatoRichiestaSintesi();
                    temp.setIdStato(rs.getString(1));
                    temp.setDescrizioneStato(rs.getString(2));
                    listaStati.add(temp);
               LOGGER.debug("Numero record trovati : " + listaStati.size());
          } catch (SQLException e) {
               LOGGER.error("Eccezione di tipo SQL : " + StringUtils.getCustomStackTrace(e));
          finally{
               LOGGER.debug("Chiusura di statement e connessione");
               databaseManager.chiudi(stmt);
               databaseManager.chiudi(conn);
          LOGGER.debug("END");
          return listaStati;
Below is another example using PreparedStatement:
     private synchronized void aggiungiIndicazioneProgetto(String idprogetto, String idrichiesta) {
          LOGGER.debug("START");
          LOGGER.debug("Creo un oggetto di tipo connessione");
          Connection conn = databaseManager.creaConnessioneDataSource(datasource);
          LOGGER.debug("Definisco una query sql");
          String sql = "INSERT INTO RICHIESTAPROGETTO (IDRICHIESTA,IDPROGETTO) VALUES (?,?)";
          LOGGER.debug("Dichiaro un oggetto di tipo preparedstatement");
          PreparedStatement stmt = null;
          try {
               LOGGER.debug("Istanzio l'oggetto statement");
               stmt = conn.prepareStatement(sql);
               LOGGER.debug("Imposto i segnalibri della query");
               stmt.setString(1, idrichiesta);
               stmt.setString(2, idprogetto);
               LOGGER.debug("Eseguo la query di inserimento del progetto");
               stmt.executeUpdate();
          } catch (SQLException e) {
               LOGGER.error("Eccezione di tipo SQL : " + StringUtils.getCustomStackTrace(e));
          finally {
               LOGGER.debug("Chiusura di statement e connessione");
               databaseManager.chiudi(stmt);
               databaseManager.chiudi(conn);
          LOGGER.debug("END");
     Which may be the cause for the described behavior?
     I hope someone help me..

My problem is the following.
If I deploy my application with the illustred datasource in my local OC4J (10.1.3 in a Standalone Environment) all work fine.
The application creates a reasonable number of connections (in ORACLE - 10g Enterprise Edition Release 10.2.0.4.0 - db I run the query verification "select count(*) from v$session where username='MYAPPLICATION'"), and overall performance is very good.
If, however, to deploy on the production machine of corporate (always 10.1.3, but obviously in Oracle Application Server Environment) the
number of connections (status 'INACTIVE') grows massively, and this is saturated in a short time.
The exception that at the end from the application is that:
java.sql.SQLException: ORA-01034: ORACLE not available
ORA-27101: shared memory realm does not exist
Linux Error: 2: No such file or directory
oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:138)
oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:316)
oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:277)
oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:272)
oracle.jdbc.driver.T4CTTIoauthenticate.receiveOsesskey(T4CTTIoauthenticate.java:243)
oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:304)
oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:430)
oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:151)
oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:32)
oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:608)
oracle.jdbc.pool.OracleDataSource.getConnection(OracleDataSource.java:218)
oracle.jdbc.pool.OracleConnectionPoolDataSource.getPhysicalConnection(OracleConnectionPoolDataSource.java:114)
oracle.jdbc.pool.OracleConnectionPoolDataSource.getPooledConnection(OracleConnectionPoolDataSource.java:77)
oracle.jdbc.pool.OracleImplicitConnectionCache.makeCacheConnection(OracleImplicitConnectionCache.java:1361)
oracle.jdbc.pool.OracleImplicitConnectionCache.getCacheConnection(OracleImplicitConnectionCache.java:441)
oracle.jdbc.pool.OracleImplicitConnectionCache.getConnection(OracleImplicitConnectionCache.java:336)
oracle.jdbc.pool.OracleDataSource.getConnection(OracleDataSource.java:286)
oracle.jdbc.pool.OracleDataSource.getConnection(OracleDataSource.java:179)
oracle.jdbc.pool.OracleDataSource.getConnection(OracleDataSource.java:159)
oracle.oc4j.sql.DataSourceConnectionPoolDataSource.getPooledConnection(DataSourceConnectionPoolDataSource.java:57)
oracle.oc4j.sql.xa.EmulatedXADataSource.getXAConnection(EmulatedXADataSource.java:92)
oracle.oc4j.sql.spi.ManagedConnectionFactoryImpl.createXAConnection(ManagedConnectionFactoryImpl.java:211)
oracle.oc4j.sql.spi.ManagedConnectionFactoryImpl.createManagedConnection(ManagedConnectionFactoryImpl.java:170)
com.evermind.server.connector.ApplicationConnectionManager.createManagedConnection(ApplicationConnectionManager.java:1377)
oracle.j2ee.connector.ConnectionPoolImpl.createManagedConnectionFromFactory(ConnectionPoolImpl.java:327)
oracle.j2ee.connector.ConnectionPoolImpl.access$800(ConnectionPoolImpl.java:98)
also I add the other attributes of Connection Pool of the Datasource:
Connections:
Initial size of Connection Cache = 0
Minimum Number of Connections = 0
Maximum Number of Connections = -1
Connection Retry Interval (seconds) = 1
Maximum Connection Attempts = 3
Maximum Number of Statements Cached = 0
Lower Threshold Limit On Pool (%)= 20
Validate Connection = False
What I can do?
many thanks..

Connection pool not re-establishing connections, throwing exception instead

Hello,
I've just set up a connection pool on the sun java system application server 8 for a MySQL database using the official mysql-connector/j 5.0. Everything is working great, except when the connections timeout (or i kill them all manually from the database server) and then request a page that needs to use the DataSource object, the following exception is thrown:
Exception thrown: com.mysql.jdbc.CommunicationsException -- Communications link failure due to underlying exception:
** BEGIN NESTED EXCEPTION **
java.io.EOFException
STACKTRACE:
java.io.EOFException
     at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1913)
     at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2304)
     at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2803)
     at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1573)
     at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1665)
     at com.mysql.jdbc.Connection.execSQL(Connection.java:3118)
     at com.mysql.jdbc.Connection.execSQL(Connection.java:3047)
     at com.mysql.jdbc.Statement.executeQuery(Statement.java:1166)
     at com.mysql.jdbc.jdbc2.optional.StatementWrapper.executeQuery(StatementWrapper.java:705)
     at beans.MySessionBean.businessMethod(MySessionBean.java:73)
     at org.apache.jsp.index_jsp._jspService(index_jsp.java:70)
     at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:105)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:860)
     at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:336)
     at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)
     at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:251)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:860)
     at sun.reflect.GeneratedMethodAccessor98.invoke(Unknown Source)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
     at java.lang.reflect.Method.invoke(Method.java:585)
     at org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:249)
     at java.security.AccessController.doPrivileged(Native Method)
     at javax.security.auth.Subject.doAsPrivileged(Subject.java:517)
     at org.apache.catalina.security.SecurityUtil.execute(SecurityUtil.java:282)
     at org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:165)
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:257)
     at org.apache.catalina.core.ApplicationFilterChain.access$000(ApplicationFilterChain.java:55)
     at org.apache.catalina.core.ApplicationFilterChain$1.run(ApplicationFilterChain.java:161)
     at java.security.AccessController.doPrivileged(Native Method)
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157)
     at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:263)
     at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:551)
     at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:225)
     at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:173)
     at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:551)
     at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
     at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:551)
     at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:132)
     at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:551)
     at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:933)
     at org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:185)
     at com.sun.enterprise.web.connector.grizzly.ProcessorTask.process(ProcessorTask.java:653)
     at com.sun.enterprise.web.connector.grizzly.ProcessorTask.process(ProcessorTask.java:534)
     at com.sun.enterprise.web.connector.grizzly.ProcessorTask.doTask(ProcessorTask.java:403)
     at com.sun.enterprise.web.connector.grizzly.WorkerThread.run(WorkerThread.java:55)
** END NESTED EXCEPTION **
Last packet sent to the server was 16 ms ago.What could be wrong?
Thank you.

The code is here:
    public String businessMethod() {
        //TODO implement businessMethod
        try
            InitialContext ic = new InitialContext();
            Object obj = ic.lookup("jdbc/MyDS");
            System.out.println("Object is: " + obj + " | Class is: " + obj.getClass().getName());
            DataSource ds = (DataSource)obj;
            Connection conn = ds.getConnection();
            Statement stmt = conn.createStatement();
            ResultSet rs = stmt.executeQuery("SELECT a,b FROM test");
            String ret = "";
            while(rs.next())
                ret += rs.getString(1) + " - " + rs.getString(2) + "<br/>";
            conn.close();
            return ret;
        catch(Exception e)
            return "Exception thrown: " + e.getClass().getName() + " -- " + e.getMessage();
    }On the server, it is set up as XADataSource. I don't really have a big need for distributed transactions, but does it hurt badly to use it anyways? Could it be causing this problem?

Connection Pool - unable to establish connection for one or more OC4J inst.

Hi.
I'm using Oracle JDeveloper 10.1.3.1 to develop some app. Database is Oracle XE 10.2.0. Application server is Oracle Aplication Server 10.1.3.1
After create a needed code, I' v tried establish Connection Pool. When I' v tested connection, next errors was occurred:
Unable to establish connection for one or more OC4J instances<<
Home on admin.FRIEND-6843859F - Failed due to error: "Exception occurred testing connection. Exception: java.sql.SQLException: invalid arguments in call."<<"FRIEND-6843859F " is Computer name where Application server is installed.
--Database is started.
--App.server processes are started.
How can I solve this problem?
Thanx

If you are using ADF "BC" Jdev will not support more than one connection
I've tryied and always gives a errors.

Connection pooling is not really connection pooling? Right?

Here's what I don't understand, I'm trying to pool connections but everywhere I look I see the following code:
Connection con = null;
try {
con = dataSource.getConnection("username", "password");
} catch (Exception ex}
finally {
con.close();
Why is the connection closed? Isn't it supposed to be "pooled"? I have read that connections need to be closed to be reused, then what's the point of "pooling connections"? I mean, I have closely followed MySQL server connections and appears that connections are indeed closed, apparently, what "connection pooling" does is save some connection information (which is what apparently is the only thing that is "pooled") which is used to establish connections instead of reusing them.
When I start my Java application, DataSource.getConnection() creates a connection and MySQL Administrator shows a new connection in a list of connections to MySQL. I get com.mysql.jdbc.Connection@13e6657 for that connection. After con.close() is called, that connection is removed from the list of connections and when DataSource.getConnection() is called again, I get com.mysql.jdbc.Connection34o3422 and a new connection shows up in MySQL Administrator.
So what's the point in calling this "connection pooling"? I mean, this isn't really pooling connection but rather saving some data in the memory that is used to create connections, not saving them.

^ The fact that a connection is pooled is usually abstracted away from the client, such that a call to the Connection's close() method doesn't actually close the connection, but instead returns it to the pool. The example you cited above says as much. The code that @OP posted could very easily be pooled behind the scenes.
Message was edited by:
bckrispi

How to purge connection pool on stale on connections

Hello
Our problem is when we are required to reboot the database then we have to reboot all application servers.
Is there a way we can avoid app servers reboot.
app server code is in VB 6.0 and .NET 1.1 (using odp.net for .net)
in a sample application what we found that the ADO (using OraOLEDB) returns a connection where the connection state is open even after database reboot, but when try to use the connection object it throws an exception like end-of-line etc.
so is there a way to clean up the connection pool or reset ole db connection manger.
Any help will be greatly appreciated
Thanks

You're using both ODP and OLEDB then?
ODP has a ClearPool method on a connection you can call, useful for just this situation.
OLEDB connection pooling is done by the OLEDB framework provided by Microsoft, not by the provider itself. I dont know of any way to clear out the pool apart from restarting the application.
Hope it helps, corrections/comments welcome
Greg

Connection pool running out of connections

Hi all,
I am using Oracle's connection pool implementation:
OracleConnectionPoolDataSource dbConnection;
OracleConnectionCacheImpl connectionPool;
and tomcat 3 and 4. Sometimes on Tomcat 4 (Linux) I see that the connections are not being reutilized and therefore I run out of free connections. The same application runs fine on NT and Tomcat 3 and 4. I checked all my methods and all have a close(connection) in my finally{} and besides this the problem only happens once in a while and the program is using the same methods all the time. Anybody has a clue about what could the issue be?
Thanks,
A.

have u tried setCacheScheme?

Connection Pooling: how many active connections?

Hi, everybody.
I have a very simple question about connection pooling...
How many active connections should a database see once a connection pool has been opened?
I mean, it should see only one connection (the pool itself) at any time, or the number of "logical" active connections in that moment?
Thanks for any answer.

Sorry...
This is the wrong forum, I posted again my question in the JDBC Forum...

Connection pooling unable to close connection on Oracle 9i 64bit

Hi there,
We have a Oracle 9i 64 bit server housed on a Solaris 64bit box. Earlier we had a 8i on a solaris 32 bit and things were fine. But after having migrated to 9i, we have been facing a peculiar issue where in the connections being opened by the application do not close/expire. We never had this problem on the 8i box.
System spec:
Solaris 64bit ver 8
JDK 1.4 JDBC thin drivers(ojdbc14.jar)
JDBC 2.0
Oracle 9.2.0.8 (64bit)
The application is housed on a 32 bit Solarix box and runs on Tomcat4.1.
Has anyone seen such probs before?? ...any ideas(quick ones) will be appreciated!
Anybody

Hi,
I did a oracle trace of the issue and this is what i get from the trace
DRVR OPER OracleConnection.setAutoCommit(autoCommit): return
DRVR OPER OracleConnection.setReadOnly(readOnly=false)
DRVR SQLS SQL: "SET TRANSACTION READ WRITE"
DRVR OPER OracleConnection.getDefaultFixedString() returning false
DRVR OPER ResultSetUtil.needIdentifier(typeCode=1): return: false
DRVR OPER OraclePreparedStatement.execute()
DRVR OPER OraclePreparedStatement.executeUpdate()
DRVR SQLS Input SQL: "SET TRANSACTION READ WRITE"
DRVR OPER OracleConnection.getAutoCommit() returned true
DRVR OPER OracleStatement.cleanupForBatching()
DRVR OPER OraclePreparedStatement.sendBatch()
DRVR SQLS SQL: "{call PKG_REASSIGN.I01_REASSIGN(?,?,?,?,?,?)}"
DRVR OPER OracleConnection.getDefaultFixedString() returning false
DRVR OPER ResultSetUtil.needIdentifier(typeCode=1): return: false
DRVR SQLS sql=<{call PKG_REASSIGN.I01_REASSIGN(?,?,?,?,?,?)}>
DRVR SQLS Input SQL: "{call PKG_REASSIGN.I01_REASSIGN(?,?,?,?,?,?)}"
DRVR SQLS sql=<{call PKG_REASSIGN.I01_REASSIGN(?,?,?,?,?,?)}>
DRVR OPER OraclePreparedStatement.setBigDecimal(paramIndex=1, x=790846)
DRVR OPER OraclePreparedStatement.setString(paramIndex=2, x=FBGJ)
DRVR OPER OraclePreparedStatement.setString(paramIndex=3, x=BALMKR01)
DRVR OPER OraclePreparedStatement.setString(paramIndex=4, x=IMRVER71)
DRVR OPER OraclePreparedStatement.setString(paramIndex=5, x=10.128.28.245)
DRVR OPER OracleCallableStatement.registerOutParameter(paramIndex=6, sqlType=2, scale=0, maxLength=-1)
DRVR OPER OracleCallableStatement.registerOutParameterBytes(paramIndex=6, sqlType=2, scale=0, maxLength=-1)
DRVR OPER OracleConnection.setAutoCommit(autoCommit=false)
DRVR OPER OracleConnection.setAutoCommit(autoCommit): return
DRVR OPER OraclePreparedStatement.execute()
DRVR OPER OraclePreparedStatement.executeUpdate()
DRVR OPER OracleConnection.getAutoCommit() returned false
DRVR OPER OracleStatement.cleanupForBatching()
DRVR OPER OracleCallableStatement.sendBatch()
Performing a pooledConnection.notifyListener() in ConnectionImpl.class
Doing a getConnection() in Jdbc2PoolDataSource
DRVR OPER OracleConnection.setAutoCommit(autoCommit=true)
DRVR OPER OracleConnection.setAutoCommit(autoCommit): return
DRVR OPER OracleConnection.setReadOnly(readOnly=false)
DRVR SQLS SQL: "SET TRANSACTION READ WRITE"
DRVR OPER OracleConnection.getDefaultFixedString() returning false
DRVR OPER ResultSetUtil.needIdentifier(typeCode=1): return: false
DRVR OPER OraclePreparedStatement.execute()
DRVR OPER OraclePreparedStatement.executeUpdate()
DRVR SQLS Input SQL: "SET TRANSACTION READ WRITE"
DRVR OPER OracleConnection.getAutoCommit() returned true
DRVR OPER OracleStatement.cleanupForBatching()
DRVR OPER OraclePreparedStatement.sendBatch()
com.*********.common.serviceexecutor.ServiceExecutorException: com.*********.common.exception.SCBBaseException: SQL Exception occured while getting connection from ConnectionPool in SQLMassRetrieveExecutor
at com.*********.common.serviceexecutor.Service.executeMethodsInOrder(Unknown Source)
at com.*********.common.serviceexecutor.Service.execute(Unknown Source)
at com.*********.common.serviceexecutor.ServiceDefinition.executeServices(Unknown Source)
at com.*********.common.serviceexecutor.StatelessServiceExecutorImpl.executeServiceDefinition(Unknown Source)
at com.*********.common.sessionutil.PageManager.executeServiceExecutor(Unknown Source)
at com.*********.common.sessionutil.PageManager.executeMethod(Unknown Source)
at com.*********.common.sessionutil.PageManager.getFirstPage(Unknown Source)
at com.*********.common.sessionutil.PageManager.getPages(Unknown Source)
at com.*********.sci.view.action.VerifyQueueListAction.perform(VerifyQueueListAction.java:124)
at org.apache.struts.action.ActionServlet.processActionPerform(ActionServlet.java:1787)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1586)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:510)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:684)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:432)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:356)
at org.apache.struts.action.ActionServlet.processActionForward(ActionServlet.java:1759)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1596)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:510)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:247)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at com.*********.sci.appservice.commonservices.FilterNew.doFilter(FilterNew.java:23)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:213)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:256)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardContext.invoke(StandardContext.java:2417)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:180)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.valves.ErrorDispatcherValve.invoke(ErrorDispatcherValve.java:171)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:172)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:641)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:174)
at org.apache.catalina.core.StandardPipeline$StandardPipelineValveContext.invokeNext(StandardPipeline.java:643)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:480)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:995)
at org.apache.ajp.tomcat4.Ajp13Processor.process(Ajp13Processor.java:457)
at org.apache.ajp.tomcat4.Ajp13Processor.run(Ajp13Processor.java:576)
at java.lang.Thread.run(Thread.java:536)
Caused by: com.*********.common.exception.SCBBaseException: SQL Exception occured while getting connection from ConnectionPool in SQLMassRetrieveExecutor
at com.*********.common.dbexecutor.SQLMassRetrieveExecutor.<init>(Unknown Source)
at com.*********.common.dbexecutor.ConnectionRetriever.getInstance(Unknown Source)
at com.*********.sci.appservice.queue.VerifyQueueListService.getDatabaseRowSetConnection(VerifyQueueListService.java:96)
at com.*********.sci.appservice.queue.VerifyQueueListService.getVerifyQueueList(VerifyQueueListService.java:157)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
... 51 more
Caused by: java.sql.SQLException: ORA-01453: SET TRANSACTION must be first statement of transaction
at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134)
at oracle.jdbc.ttc7.TTIoer.processError(TTIoer.java:289)
at oracle.jdbc.ttc7.Oall7.receive(Oall7.java:590)
at oracle.jdbc.ttc7.TTC7Protocol.doOall7(TTC7Protocol.java:1973)
at oracle.jdbc.ttc7.TTC7Protocol.parseExecuteFetch(TTC7Protocol.java:1119)
at oracle.jdbc.driver.OracleStatement.executeNonQuery(OracleStatement.java:2191)
at oracle.jdbc.driver.OracleStatement.doExecuteOther(OracleStatement.java:2064)
at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:2989)
at oracle.jdbc.driver.OraclePreparedStatement.executeUpdate(OraclePreparedStatement.java:658)
at oracle.jdbc.driver.OraclePreparedStatement.execute(OraclePreparedStatement.java:736)
at oracle.jdbc.driver.OracleConnection.setReadOnly(OracleConnection.java:1631)
at com.*********.common.connectionpool.adapter.ConnectionImpl.setReadOnly(ConnectionImpl.java:203)
at com.*********.common.connectionpool.newp.Jdbc2PoolDataSource.getConnection(Jdbc2PoolDataSource.java:645)
at com.*********.common.connectionpool.newp.Jdbc2PoolDataSource.getConnection(Jdbc2PoolDataSource.java:534)
... 59 more
Is oracle missing a COMMIT before it is passing the SET TRANSACTION statement??. and is there any relation between the AutoCommit and the Isolation level?

Listener EA2: database connection pool and connection revalidation

Hi all,
As one can expect from early adopter release there could be some bugs but I can't find any references in forum to my situation:
* My 11g XE database and listener are starting as windows services when server boots operating system (Windows Server 2003 R2).
* I configured my web server (unsupported Jetty 9.0.0.M1) to start as windows service when operating system starts.
* Apex Listener 2.0.0.268.17.05 configured to connect with XE using JDBC thin driver with default settings (initial pool size 3, max statements 10, min connections 1, max connections 10, inactivity timeout 1800, abandoned connection timeout 900)
* Because web server starts a bit faster than Oracle database when apex connects first time it gets "ORA-12528, TNS:listener: all appropriate instances are blocking new connections" (could be that database still starting but already registered service with listener)
* From listener.log file I can see that all further connections made from Apex listener succeeds
* When I try to open any apex page with browser I am getting 404 error and apex listener logs error (*time is 2 days after system startup*):
2012-11-30 3:56:02 PM oracle.dbtools.common.config.db.DatabaseConfig badConfiguration
SEVERE: The pool named: apex is not correctly configured, error: Listener refused the connection with the following error:
ORA-12528, TNS:listener: all appropriate instances are blocking new connections
ConnectionPoolException [error=BAD_CONFIGURATION]
     at oracle.dbtools.common.jdbc.ConnectionPoolException.badConfiguration(ConnectionPoolException.java:62)
     at oracle.dbtools.common.config.db.DatabaseConfig.badConfiguration(DatabaseConfig.java:146)
     at oracle.dbtools.common.config.db.DatabaseConfig.createPool(DatabaseConfig.java:168)
     at oracle.dbtools.common.config.db.DatabaseConfig.getConnection(DatabaseConfig.java:68)
     at oracle.dbtools.common.jdbc.ora.OraPrincipal.connection(OraPrincipal.java:25)
     at oracle.dbtools.apex.ModApexContext.getConnection(ModApexContext.java:320)
     at oracle.dbtools.apex.Procedure.getProcedure(Procedure.java:166)
     at oracle.dbtools.apex.OWA.validateProcedure(OWA.java:384)
     at oracle.dbtools.apex.security.Security.isValidRequest(Security.java:171)
     at oracle.dbtools.apex.ModApex.validateRequest(ModApex.java:233)
     at oracle.dbtools.apex.ModApex.doGet(ModApex.java:79)
     at oracle.dbtools.apex.ModApex.service(ModApex.java:263)
     at oracle.dbtools.rt.web.HttpEndpointBase.modApex(HttpEndpointBase.java:288)
     at oracle.dbtools.rt.web.HttpEndpointBase.service(HttpEndpointBase.java:127)
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:848)
     at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:665)
     <... Jetty web server stack ...>
     at java.lang.Thread.run(Unknown Source)
2012-11-30 3:56:02 PM oracle.dbtools.rt.web.HttpEndpointBase modApex
* Oracle listener log for same time (no errors here):
30-NOV-2012 15:56:01 * (CONNECT_DATA=(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=SYSTEM))(SERVICE_NAME=xe)(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=SYSTEM))) * (ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1078)) * establish * xe * 0
30-NOV-2012 15:56:01 * (CONNECT_DATA=(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=SYSTEM))(SERVICE_NAME=xe)(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=SYSTEM))) * (ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1079)) * establish * xe * 0
30-NOV-2012 15:56:01 * (CONNECT_DATA=(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=SYSTEM))(SERVICE_NAME=xe)(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=SYSTEM))) * (ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1080)) * establish * xe * 0
30-NOV-2012 15:56:01 * (CONNECT_DATA=(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=SYSTEM))(SERVICE_NAME=xe)(CID=(PROGRAM=JDBC Thin Client)(HOST=__jdbc__)(USER=SYSTEM))) * (ADDRESS=(PROTOCOL=tcp)(HOST=127.0.0.1)(PORT=1081)) * establish * xe * 0
* For some reason apex listener keeps first connection status and won't try to establish new connection if first attempt finished with ORA-12528
* The same scenario is valid when at time of web server start oracle database/listener is not available - even if database and listener starts and apex successfully establishes further connections all apex pages gets 404 error
* If I restart web server windows service (while oracle db and listener still running) browser opens apex pages without errors and apex listener does not log any errors
* I know that I can avoid this error delaying start of web server windows service but it would be nice to have production release 2.x without such bugs

Hi,
Is there any way to use the connection pool or Datasource while connecting to database?If I am using a stateless sesssion bean and using a Data Access layer which just creates a database session to write the persistence toplink objects how I can make use of application server connection pool?Hi Vinod,
Yes, TopLink allows you to use the app server's connection pooling and transaction services. Chapter 2 of the Oracle9iAS TopLink Foundation Library Guide provides details as do the TopLink examples. The easiest way to set this up is by using the sessions.xml file. The sample XML below is from the file <toplink903>\examples\ias\examples\ejb\sessionbean\sessions.xml. Here we are adding the datasource defined in OC4J and specifying that we are using the OC4J transaction controller also.
<login>
<user-name>sa</user-name>
<password></password>
<datasource>java:comp/env/jdbc/ejbJTSDataSource</datasource>
<uses-external-transaction-controller>true</uses-external-transaction-controller>
<uses-external-connection-pool>true</uses-external-connection-pool>
</login>
<external-transaction-controller-class>oracle.toplink.jts.oracle9i.Oracle9iJTSExternalTransactionController</external-transaction-controller-class>
When using this approach you need to change your TopLink code slightly in the EJB methods:
a. Acquire the ACTIVE unit of work from the server
session (again, see the EmployeeSessionEJB code
example) with something like:
UnitOfWork uow = clientSession.getActiveUnitOfWork();
b. Calls to uow.commit() can be ommitted or commented out
because the EJB will handle this. Note that of course
the methods you create in the EJB that are using this
approach must have TX Required (default).
Hope this helps.
Pete

Using database connection in a servlet and get errors after 8 hours

Hey,
I'm running a poker script using applet/servlets and it works great. But for some reason about about 8 hours that database layer stops working. At first I thought it was the connections to mySQL that were timing out (because im using connection pooling) but after turning pooling off (I now create the connection each time) I'm still seeing that same error (I can create a connection but when I do an action ex. like a select statment I get an error). What i'm wondering could it be that the driver I load with Class.forName() some how unloads it's self after x amount of time not being used? Not sure if that is it but if anyone could give me some insight that would be great. The Error i recieve is below:
INFO: Database Event:DatabaseController: Error executing database query.
ERROR: Communications link failure due to underlying exception:
** BEGIN NESTED EXCEPTION **
java.net.SocketException
MESSAGE: Software caused connection abort: recv failed
STACKTRACE:
java.net.SocketException: Software caused connection abort: recv failed
     at java.net.SocketInputStream.socketRead0(Native Method)
     at java.net.SocketInputStream.read(Unknown Source)
     at com.mysql.jdbc.util.ReadAheadInputStream.fill(ReadAheadInputStream.java:104)
     at com.mysql.jdbc.util.ReadAheadInputStream.readFromUnderlyingStreamIfNecessary(ReadAheadInputStream.java:144)
     at com.mysql.jdbc.util.ReadAheadInputStream.read(ReadAheadInputStream.java:172)
     at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1839)
     at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2288)
     at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2784)
     at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1531)
     at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1622)
     at com.mysql.jdbc.Connection.execSQL(Connection.java:2370)
     at com.mysql.jdbc.Connection.execSQL(Connection.java:2297)
     at com.mysql.jdbc.Statement.executeQuery(Statement.java:1183)
     at com.softnet.database.DatabaseController.executeDatabaseQuery(DatabaseController.java:190)
     at com.softnet.games.GameServer.validateUser(GameServer.java:438)
     at com.softnet.games.GameServer.handleData(GameServer.java:113)
     at com.softnet.network.HttpConnectionThread.run(HttpServletListener.java:191)
** END NESTED EXCEPTION **
I know the query is good because it works all other times just not after about 8 hours.
--Z3r0CooL

Hey,
Thanks for the responces. For the connection pooling I would open 5 connections and keep them open. So i though maybe after 8 hours after not being used they would timeout. Thats why i turned off conection pooling and create a new connection each time. Anyways i'll post the code below incase i made a mistake somewhere.
package com.softnet.database;
/************************ DatabaseControler **************************/
import java.sql.*;
import java.util.*;
import com.softnet.database.DatabaseConnectionPool;
import com.softnet.database.DatabaseSettings;
public class DatabaseController
implements DatabaseListener
     //Used to make sure the database driver is loaded
     private boolean databaseDriverState = false;
     //Used to store a database connection
     private Connection databaseConnection = null;
     //If to user connection pooling or not
     private boolean useConnectionPooling = false;
     //Used to hold the connection pool varible
     private DatabaseConnectionPool connectionPool = null;
     //Used to store database settings
     private DatabaseSettings databaseSettings;
     //Used to hold the DatabaseController listeners
     private List databaseControllerListeners = new ArrayList();
     //min number of connections for connection pool
     private int minNumberOfConnections = 1;
     //max number of connections for connection pool -1 is unlimited
     private int maxNumberOfConnections = -1;
     //DatabaseController Constructors
     public DatabaseController(DatabaseSettings databaseSettings)
          this.databaseSettings = databaseSettings;
          databaseDriverState = loadDatabaseDriver(databaseSettings.getDatabaseDriver());
     public DatabaseController(DatabaseSettings databaseSettings, boolean useConnectionPooling, int minNumberOfConnections, int maxNumberOfConnections)
          this.databaseSettings = databaseSettings;
          this.useConnectionPooling = useConnectionPooling;
          this.minNumberOfConnections = minNumberOfConnections;
          this.maxNumberOfConnections = maxNumberOfConnections;
          if(useConnectionPooling == true)
               connectionPool = new DatabaseConnectionPool(databaseSettings, minNumberOfConnections, maxNumberOfConnections);
               connectionPool.addDatabaseListener(this);
          else
               databaseDriverState = loadDatabaseDriver(databaseSettings.getDatabaseDriver());
     public DatabaseController() {}
     //Database Settings Get/Set
     public DatabaseSettings getDatabaseSettings()
          return databaseSettings;
     public void setDatabaseSettings(DatabaseSettings databaseSettings)
          this.databaseSettings = databaseSettings;
     //Connection Pooling Get/Set
     public boolean getConnectionPooling()
          return useConnectionPooling;
     public void setConnectionPooling(boolean useConnectionPooling, int minNumberOfConnections, int maxNumberOfConnections)
          this.useConnectionPooling = useConnectionPooling;
          this.minNumberOfConnections = minNumberOfConnections;
          this.maxNumberOfConnections = maxNumberOfConnections;
          if(useConnectionPooling == true)
               if(connectionPool == null)
                    connectionPool = new DatabaseConnectionPool(databaseSettings, minNumberOfConnections, maxNumberOfConnections);
                    connectionPool.addDatabaseListener(this);
          else
               if(connectionPool != null)
                    connectionPool.destroyConnections();
                    connectionPool.removeDatabaseListener(this);
                    connectionPool = null;
     //Return if there connected
     public boolean isConnected()
          boolean isConnected;
          if(databaseConnection != null)
               isConnected = true;
          else
               isConnected = false;
          return isConnected;
     //Used to connect to database or get a connection for the connection pool
     public void connect()
          if(databaseDriverState == false)
               databaseDriverState = loadDatabaseDriver(databaseSettings.getDatabaseDriver());
          //If we dont have a current connection, make one
          if(databaseConnection == null && databaseDriverState == true)
               if(useConnectionPooling == false)
                    try
                         databaseConnection = DriverManager.getConnection(databaseSettings.getDatabaseURL(), databaseSettings.getUserName(), databaseSettings.getUserPassword());
                    catch (SQLException sqle)
                         //Raise event
                         raiseDatabaseEvent("DatabaseController: Error connecting to database. \nERROR: " + sqle.getMessage());
                         databaseConnection = null;
               else
                    databaseConnection = connectionPool.getConnection();
     //Used to disconnect from the database or give back the connection to the connection pool
     public void disconnect()
          if(databaseConnection != null)
               if(useConnectionPooling == false)
                    try
                         //Close DB Connection
                         databaseConnection.close();
                    catch(SQLException ignore) {}
                    finally
                         databaseConnection = null;
               else
                    connectionPool.returnConnection(databaseConnection);
                    databaseConnection = null;
     public ResultSet executeDatabaseQuery(String sSQL)
          ResultSet databaseResult = null;
          if(databaseConnection != null)
               try
                    Statement databaseStatement = databaseConnection.createStatement();
                    databaseResult = databaseStatement.executeQuery(sSQL);
               catch(SQLException sqle)
                    //Raise event
                    raiseDatabaseEvent("DatabaseController: Error executing database query.\nSQL: " + sSQL + "\nERROR: " + sqle.getMessage());
          return databaseResult;
     public int executeDatabaseUpdate(String sSQL)
          int rowsAffected = -1;
          if(databaseConnection != null)
               try
                    Statement databaseStatement = databaseConnection.createStatement();
                    rowsAffected = databaseStatement.executeUpdate(sSQL);
               catch(SQLException sqle)
                    //Raise event
                    raiseDatabaseEvent("DatabaseController: Error executing database update.\nSQL: " + sSQL + "\nERROR: " + sqle.getMessage());
          return rowsAffected;
     //Used to load the Database Driver
     private boolean loadDatabaseDriver(String databaseDriver)
          boolean driverLoaded;
          if(databaseDriver.equals("") == false)
               try
                    //Load Database Driver
                    Class.forName(databaseDriver).newInstance();
                    driverLoaded = true;
               catch (Exception e)
                    //Raise event
                    raiseDatabaseEvent("DatabaseController: Error loading database driver. \nERROR: " + e.getMessage());
                    driverLoaded = false;
          else
               driverLoaded = false;
          return driverLoaded;
     //Wrap the DatabaseConnectionPool Error to the DatabaseController
     public void databaseEventOccurred(DatabaseEvent de)
          raiseDatabaseEvent(de.getErrorMessage());
     //Event Handling Code
     //Used to add database listeners (Its sync'd so you can change the listeners when firing an event)
public synchronized void addDatabaseListener(DatabaseListener databaseControllerListener)
databaseControllerListeners.add(databaseControllerListener);
//Used to remove a listener from the list (Its sync'd so you can change the listeners when firing an event)
public synchronized void removeDatabaseListener(DatabaseListener databaseControllerListener)
databaseControllerListeners.remove(databaseControllerListener);
//Used to send the raise event to the listeners
private synchronized void raiseDatabaseEvent(String databaseError)
DatabaseEvent databaseEvent = new DatabaseEvent(this, databaseError);
Iterator listeners = databaseControllerListeners.iterator();
while(listeners.hasNext())
     DatabaseListener listener = (DatabaseListener) listeners.next();
listener.databaseEventOccurred(databaseEvent);
/********************* DatabaseConnectionPool **************/
package com.softnet.database;
import java.io.*;
import java.sql.*;
import java.util.*;
import com.softnet.database.*;
import com.softnet.database.DatabaseSettings;
public class DatabaseConnectionPool
     //min number of connections
     private int minNumberOfConnections = 1;
     //max number of connections -1 is unlimited
     private int maxNumberOfConnections = -1;
     //Store the connections
     protected Hashtable databaseConnections = null;
     //Database Info
     protected DatabaseSettings databaseSettings;
     //to hold Driver state
     private boolean databaseDriverState = false;
     //To hold connection checker
     private DatabaseConnectionCheck connectionChecker = null;
     //Used to hold the DatabaseConnectionPool listeners
     private List databaseConnectionPoolListeners = new ArrayList();
     public DatabaseConnectionPool(DatabaseSettings databaseSettings, int minNumberOfConnections, int maxNumberOfConnections)
          this.databaseSettings = databaseSettings;
          this.minNumberOfConnections = minNumberOfConnections;
          this.maxNumberOfConnections = maxNumberOfConnections;
          //Load Driver
          databaseDriverState = loadDatabaseDriver(databaseSettings.getDatabaseDriver());
          //Create connection
          createConnections();
     public DatabaseConnectionPool(int minNumberOfConnections, int maxNumberOfConnections)
          this.minNumberOfConnections = minNumberOfConnections;
          this.maxNumberOfConnections = maxNumberOfConnections;
     //Database Settings Get/Set
     public DatabaseSettings getDatabaseSettings()
          return databaseSettings;
     public void setDatabaseSettings(DatabaseSettings databaseSettings)
          this.databaseSettings = databaseSettings;
     //Driver State Get
     public boolean getDatabaseDriverState()
          return databaseDriverState;
     public void createConnections()
          if(databaseDriverState == false)
               databaseDriverState = loadDatabaseDriver(databaseSettings.getDatabaseDriver());
          //Create all connections and load the minimum in the Hashtable
          if(databaseConnections == null)
               if(databaseDriverState == true && minNumberOfConnections != 0)
                    databaseConnections = new Hashtable();
                    for(int i = 0; i < minNumberOfConnections; i++)
                         try
                              databaseConnections.put(DriverManager.getConnection(databaseSettings.getDatabaseURL(), databaseSettings.getUserName(), databaseSettings.getUserPassword()), Boolean.FALSE);
                         catch(SQLException sqle)
                              //Problem break loop and destroy any connections
                              destroyConnections();
                              //Raise event
                              raiseDatabaseEvent("DatabaseConnectionPool: Error creating database connections. \nERROR: " + sqle.getMessage());
                              break;
          //If no connection check exists create one
          if(connectionChecker == null)
               connectionChecker = new DatabaseConnectionCheck(this);
               connectionChecker.start();
     public Connection getConnection()
          Connection connection = null;
          boolean errorWithConnection = false;
          Enumeration connections = databaseConnections.keys();
          synchronized (databaseConnections)
               while(connections.hasMoreElements())
                    errorWithConnection = false;
                    connection = (Connection) connections.nextElement();
                    Boolean state = (Boolean) databaseConnections.get(connection);
                    //If connection is not used, use it.
                    if(state == Boolean.FALSE)
                         try
                              connection.setAutoCommit(true);
                         catch(SQLException e)
                              //Problem with connection remove connection and replace it
                              databaseConnections.remove(connection);
                              try
                                   connection = DriverManager.getConnection(databaseSettings.getDatabaseURL(), databaseSettings.getUserName(), databaseSettings.getUserPassword());
                              catch(SQLException sqle)
                                   errorWithConnection = true;
                         if(errorWithConnection == false)
                              // Update the Hashtable to show this one's taken
                              databaseConnections.put(connection, Boolean.TRUE);
                              // Return the connection
                              return connection;
               //All connections being used check to max to see if we can make a new one
               if(maxNumberOfConnections == -1 || maxNumberOfConnections > databaseConnections.size())
                    try
                         connection = DriverManager.getConnection(databaseSettings.getDatabaseURL(), databaseSettings.getUserName(), databaseSettings.getUserPassword());
                    catch(SQLException sqle)
                         errorWithConnection = true;
                    if(errorWithConnection == false)
                         databaseConnections.put(connection, Boolean.TRUE);
                         return connection;
          //If not connections free and max connections reached wait for a free connection
          return getConnection();
     public void returnConnection(Connection connection)
          boolean errorWithConnection = false;
          //Make sure connection still works
          try
               connection.setAutoCommit(true);
          catch(SQLException e)
               //Problem with connection remove connection and replace it
               databaseConnections.remove(connection);
               try
                    connection = DriverManager.getConnection(databaseSettings.getDatabaseURL(), databaseSettings.getUserName(), databaseSettings.getUserPassword());
               catch(SQLException sqle)
                    errorWithConnection = true;
          if(errorWithConnection == false)
               databaseConnections.put(connection, Boolean.FALSE);
     public void destroyConnections()
          Connection connection = null;
          if(databaseConnections != null)
               //Close all connections
               Enumeration connections = databaseConnections.keys();
               while (connections.hasMoreElements())
                    connection = (Connection) connections.nextElement();
                    try
                         connection.close();
                    catch(SQLException ignore) {}
               //Free up hashtable
               databaseConnections = null;
     private boolean loadDatabaseDriver(String databaseDriver)
          boolean driverLoaded;
          if(databaseDriver.equals("") == false)
               try
                    //Load Database Driver
                    Class.forName(databaseDriver);
                    driverLoaded = true;
               catch (ClassNotFoundException cnfe)
                    //Raise event
                    raiseDatabaseEvent("DatabaseController: Error loading database driver. \nERROR: " + cnfe.getMessage());
                    driverLoaded = false;
          else
               driverLoaded = false;
          return driverLoaded;
     //Event Handling Code
     //Used to add database listeners (Its sync'd so you can change the listeners when firing an event)
public synchronized void addDatabaseListener(DatabaseListener databaseConnectionPoolListener)
databaseConnectionPoolListeners.add(databaseConnectionPoolListener);
//Used to remove a listener from the list (Its sync'd so you can change the listeners when firing an event)
public synchronized void removeDatabaseListener(DatabaseListener databaseConnectionPoolListener)
databaseConnectionPoolListeners.remove(databaseConnectionPoolListener);
//Used to send the raise event to the listeners
private synchronized void raiseDatabaseEvent(String databaseError)
DatabaseEvent databaseEvent = new DatabaseEvent(this, databaseError);
Iterator listeners = databaseConnectionPoolListeners.iterator();
while(listeners.hasNext())
     DatabaseListener listener = (DatabaseListener) listeners.next();
listener.databaseEventOccurred(databaseEvent);
class DatabaseConnectionCheck extends Thread
     private DatabaseConnectionPool connectionPool;
     DatabaseConnectionCheck(DatabaseConnectionPool connectionPool)
          this.connectionPool = connectionPool;
     public void run()
          try
               while(true)
                    //check threads every 30 seconds
                    this.sleep(300000);
                    if(connectionPool.databaseConnections != null)
                         Connection connection = null;
                         Enumeration connections = connectionPool.databaseConnections.keys();
                         synchronized (connectionPool.databaseConnections)
                              while(connections.hasMoreElements())
                                   connection = (Connection) connections.nextElement();
                                   Boolean state = (Boolean) connectionPool.databaseConnections.get(connection);
                                   //If connection is not used, use it.
                                   if(state == Boolean.FALSE)
                                        try
                                             connection.setAutoCommit(true);
                                        catch(SQLException e)
                                             //Problem with connection remove connection and replace it
                                             connectionPool.databaseConnections.remove(connection);
                                             try
                                                  connection = DriverManager.getConnection(connectionPool.databaseSettings.getDatabaseURL(), connectionPool.databaseSettings.getUserName(), connectionPool.databaseSettings.getUserPassword());
                                             catch(SQLException sqle)
                                                  connection = null;
                                             // Update the Hashtable with new connection if its not null
                                             if(connection != null)
                                                  connectionPool.databaseConnections.put(connection, Boolean.FALSE);
          catch(InterruptedException ignored) {}
Basicly the why it works is the connection pool hold the database connections. When the user needs a connection they use the database controller to request a connection (By create a instance and called the connect() method) and the connection is either created or grabed from the connection pool. After the user is done with the connection they call the disconnect() method which closes the connection or returns it to the connection pool.
--Z3r0CooL

Difference between connection pooling and simple connection

Anybody please tell me what is the Difference between connection pooling and simple connection and also where we define connection pooling and how.
Thanks
Please reply soon
amitindia

Creating and closing connection to the database is a relatively slow process. Equally connections use database resources so you can't just open as many as you want.
A connection pool maintains a number of open connections throughout the lifetime of the application. Instead of opening and closing the connections your application just "borrows" them from the pool when they're needed.
If the pool runs out of connections it will usually create new ones as needed until you reach some predefined upper limit.
A good connection pool will also manage connections which have failed for any reason, and report code which fails to return connections to the pool (ie connection leaks).
The number of connections created at startup is referred to as the "low water mark" and the maximum number that the pool will allow to be opened at any given time is the "high water mark". If no connections are available client code will generally block until one is released.
If by "defined" you mean where can you get a working implementation then your database or application server vendor is likely to provide one. Also the Apache Jakarta Commons includes [url http://jakarta.apache.org/commons/dbcp/]an implementation which you can use with any JDBC driver.
Dave.

Connection Pool and Database Sessions

Hi,
Is there any way to use the connection pool or Datasource while connecting to database?If I am using a stateless sesssion bean and using a Data Access layer which just creates a database session to write the persistence toplink objects how I can make use of application server connection pool?
Thanks,
Vinod

Hi,
Is there any way to use the connection pool or Datasource while connecting to database?If I am using a stateless sesssion bean and using a Data Access layer which just creates a database session to write the persistence toplink objects how I can make use of application server connection pool?Hi Vinod,
Yes, TopLink allows you to use the app server's connection pooling and transaction services. Chapter 2 of the Oracle9iAS TopLink Foundation Library Guide provides details as do the TopLink examples. The easiest way to set this up is by using the sessions.xml file. The sample XML below is from the file <toplink903>\examples\ias\examples\ejb\sessionbean\sessions.xml. Here we are adding the datasource defined in OC4J and specifying that we are using the OC4J transaction controller also.
<login>
<user-name>sa</user-name>
<password></password>
<datasource>java:comp/env/jdbc/ejbJTSDataSource</datasource>
<uses-external-transaction-controller>true</uses-external-transaction-controller>
<uses-external-connection-pool>true</uses-external-connection-pool>
</login>
<external-transaction-controller-class>oracle.toplink.jts.oracle9i.Oracle9iJTSExternalTransactionController</external-transaction-controller-class>
When using this approach you need to change your TopLink code slightly in the EJB methods:
a. Acquire the ACTIVE unit of work from the server
session (again, see the EmployeeSessionEJB code
example) with something like:
UnitOfWork uow = clientSession.getActiveUnitOfWork();
b. Calls to uow.commit() can be ommitted or commented out
because the EJB will handle this. Note that of course
the methods you create in the EJB that are using this
approach must have TX Required (default).
Hope this helps.
Pete

What's the difference between using a connection pool and a datasource

Howdy. I figure this is a newbie question, but I can't seem to find an
answer.
In the docs at bea, the datasource docs say
"DataSource objects provide a way for JDBC clients to obtain a DBMS
connection. A DataSource is an interface between the client program and the
connection pool. Each data source requires a separate DataSource object,
which may be implemented as a DataSource class that supports either
connection pooling or distributed transactions."
In there it says the datasource uses the connection pool, but other than
that, what is the difference between a connection pool and a datasource?

Thanks for the info. I think it makes some sense. But it's a bit greek.
I'm sure it'll make more sense the more I work with it. Thanks.
"Chuck Nelson" <[email protected]> wrote in message
news:3dcac1f5$[email protected]..
>
Peter,
Here is a more formal definition of a DataSource from the Sun site
"A factory for connections to the physical data source that thisDataSource object
represents. An alternative to the DriverManager facility, a DataSourceobject
is the preferred means of getting a connection. An object that implementsthe
DataSource interface will typically be registered with a naming servicebased
on the JavaTM Naming and Directory (JNDI) API.
The DataSource interface is implemented by a driver vendor. There arethree types
of implementations:
Basic implementation -- produces a standard Connection object
Connection pooling implementation -- produces a Connection object thatwill automatically
participate in connection pooling. This implementation works with amiddle-tier
connection pooling manager.
Distributed transaction implementation -- produces a Connection objectthat may
be used for distributed transactions and almost always participates inconnection
pooling. This implementation works with a middle-tier transaction managerand
almost always with a connection pooling manager.
Does that help clarify the distinction?
Chuck Nelson
DRE
BEA Technical Support

Struts and Connection pooling my servlet DB connections ...

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